Electric-arc lamp



(No Model.) 3 Sl1eets-Sheet 1.

T. SPENCER.

. ELECTRIC ARC LAMP. No. 556,479. Patented Mar. 17, 1896.

f Serf C'az'Z 2 2 f T INVENTOR: 750777625 527872682" By his Al/omey (m- (HEW 5 GRAHAM. PHOTU-LITWLWASHINEI'UKU 0.

(No Model.)

3 Sheets-Sheet 2. T. SPENCER. ELECTRIC ARC LAMP.

No. 556,479. Patented Ngar. 17,,1896.

war, 1 mm WITNESSES: 1 INVENTOR: A 740. & A

720772; Spencer.

5 his Atlome ANDREW B GRAHAM PNOYO-LITHQWiSNINGTDlDC.

- (No Model.) I 3 Sheets-Sheet 3.

- 4 T. SPENCER.

ELECTRIC ARC LAMP.

No. 556,479. v Patented Mar. 17,1896.

WITNESSES INVENTOR: 2 50772648 Spencer.

By his Azfomzey ANDREW EGHHMM,FHOTO'LITHQWASNINGTDMDL.

UNITED STATES PATENT OFFICE.

THOMAS SPENCER, OF PHILADELPHIA, FENNSYLVANIA.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 556,479, dated March 17, 1896.

Application filed July 1, 1895. derial No. 554,538. (No model.)

To aZZ whom it may concern.-

Be it known that I, THOMAS SPENCER, a citizen of the United States, and a resident of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Electric-Arc Lamps, of which the following is a specification.

This invention relates to electric-arc lamps.

The object of the invention is to provide a more gradual feed of the electrode or electrodes as they are consumed by the are than is ordinarily possible. The devices used in practice which most nearly approach the desired sensitiveness of feed are based upon frictional action, which is varied in degree with variations in the length of the are and permit the carbon-holder to move when the friction is reduced to a predetermined point. There is a serious defect in devices of this character, which almost excludes them from use on constant-potential circuits-namely, a liability to slip too far and permit the carbons to come into contact when the controlling-magnet is in a position in which it cannot spring the are, a result disastrous to the magnet, which is liable to be burned out, and also annoying in extinguishing the light. The object of my invention is to obviate this possibility by providing means for limiting the extent of the slip during a single movement or traverse of the magnet core or armature to a small range, in which the armature or core will be always within the magnets control, so that the latter will always be in co-operative relation to the core and cannot fail to graduate the arc to the proper length.

In carrying out my invention I provide the friction device with a series of stops or checking devices which will arrest the feed if the parts should slip by reason of shocks or sudden vibrations, but which will permit the feed to continue when actuated by the regulating-magnet. I preferably use a frictionwheel geared to the carbon-holder or its connecting' devices, upon which bears a frictionshoe mounted on or connected with the magnet armature or core. Rigidly connected with the friction-wheel is a circular row of teeth or arresting-points, in the path of which lies a stop when the magnet armature or core lies near or at the end of its stroke. \Vith such an organization if, byreason of a shock, the friction device should permit the carbon to feed too far while the magnet is energized it cannot pass beyond its control because it will be arrested by the stop.

The several features of novelty of the invention will be more particularly hereinafter described and will be definitely indicated in the claims appended to this specification.

In the accompanying drawings, which illustrate the invention, Figures 1 and 2 show sectional elevations on planes at right angles to each other of the invention as applied to a focusing-lamp. Figs. 3 and -1t are similar views of the invention as applied to a non-focusing lamp. Fig. 5 is a detail view of a modified form of feed-limiting device, and Figs. 6 and 7 are diagrams showing the difficulty my invention is designed to cure.

Referring first to Figs. 6 and 7, 1 represents an arbor fixed in a lamp-frame, upon which is journaled a frame 2 carrying a gear-train 3 at. 011 the wheel 4. is fixed a pulley, over which passes a flexible cord or chain carrying the positive and negative carbon-holders 5 G at its ends, the positive side being heavier, so that gravity tends to bring the carbons together. To the frame 2 is connected the core 7 of the regulating-solenoid placed in this type in series with the are. On the periphery of the wheel 3 is a friction-shoemounted on a pivoted arm 8, in the path of which lies a stop 0. hen the solenoid is energized the core is drawn in, withdrawing the extremity of arm 8 from the stop 9 and bringing the shoe into frictional engagement with wheel 3. Simultaneously a partial rotation of pulley a springs the are. As the carbons burn away and the arc lengthens, the solenoid weakens and permits the core to descend until lever S engages stop 9 and the friction-shoe is withdrawn from the periphery of its co-opcratin g wheel. The superior weight of the positive carbon then causes the carbons to approach each other. If, however, the lamp receives one or more shocks or is subjected to vibration there will be slip between the frictionshoe and its wheel, which will accumulate until the coil can draw in its core no farther. This condition is exemplified in Fig. 7.

willbe seen uponinspection, the core is drawn fully into its coil. The solenoid has therefore lost its control, and the carbons will remain in contact. The entire voltage is thus thrown upon the solenoid, and the latter will burn out under the large current which will flow. To avoid this contingency I provide the friction-wheel or some part of the wheel-train of which it forms a part with a row of projections 10, (see the other figures of the drawings,) and secure to the frame a projecting stop or pawl 11, which lies in the path of movement of the projection when the coil is energized and its core attracted to feeding position. Thus, evidently, a very small extent of slip will suffiee to bring the stop 11 into action and arrest the feed until the lengthening of the are permits the solenoid to lower its core and release the friction-wheel.

In the organization shown in Figs. 1 and 2 my improvements are shown applied to a focusing-lamp. There is also shown an improved mounting for the solenoid-core, which is very effective with alternating currents. The core 7 is composed of a split iron tube surrounding a rod 12 connected with a dash-pot 13 mounted on the frame of the lamp. The split tube bears against spiral springs surrounding the rod and held under tension by nuts on the rod, thus cushioning the core and dampening the disagreeable high-pitched note obtrusively conspicuous when alternatingcurrent lamps are in operation. To the dashpot are fixed leaf-springs 1i 1i, which bear on opposite sides of a stud or pin 15 set in the frame 2. The frame 2 is j ournaled on standards 10 16 at 17. 8 is the friction-lever and 9 its releasing-pin.

The carbon-carriers 5 and ii are guided by a suitable frame, which may be varied in construction as desired.

lVhile I have shown a particular form of friction-brake, I desire it to be understood that it is merely typical, and that any appropriate form might be employed; also other specific constructions for limiting the range of slip might be substitutedfor example, in Fig. 5 in lieu of the circumferential row of pins is shown a toothed wheel 10*, which cooperates with a fixed stop 11 in the same way as already described in connection with Figs. 1 and 2.

The slip checking or limiting device need not of course be mounted 011 the frietionwheel, but may with equal advantage be socured to any part of the wheel-train, the only requisite being that the movement of the feedtrain shall be arrested after a small range of movement and prevent the loss of control of the magnet over the arc-springing frame.

The lamp described in Figs. 1 and 2, as already stated, is designed for constant-potential cireuits,the solenoid bein gplaced in series relation to the are, so as to have a variable drop of voltage as the are varies in length.

In Figs. 3 and -L Ihave shown my improvcments as applied to a rack-lamp of the nonfoeusing type. The rack 17, which constitutes a carrier for the positive upper carbon, gears with a pinion 1S and moves in guides in the lamp-frame in a manner well understood by those familiar with arc-lamp construction. The pinion 18 and gea1.'-whcel '1.) are secured to the same axis and form part of a wheel-train carried by a frame 20 secured to a movable yoke 21 carrying cores 22 22. The solenoid is fixed to the lamp-frame and has two short fixed cores to magnify its tractive power. A lever is pivoted on the frame 20. It bears at one end against the lamp-frame or the fixed yoke of the magnet and at the other end is connected to a spring 2-1, which is secured at its opposite end to a spur of the frame 20. The tendency of the spring to shorten lifts frame 20 away from the lampframe, and the rack and carboncarrier rise with it, springing an arc, whereas the mag net draws its core downwardly and opposes the spring. I11 this type of lamp, designed for constant-current circuits,the pair of solenoids is in shunt to the are. As the carbons burn away, an increased pull of the solenoid weakens the tension of the sprin ill and lowers the wheel-train frame. The frictionlever 25 pivoted in the frame then rests on stop 26 and frees the friction-wheel 27. In the normal operation of the lamp the pins in friction-wheel 27 will be obstructed if the friction-wheel should slip by stop 28; but when the solcnoid'cores are drawn insufficiently the pins clear the lower edge of the stop and the feed is not obstructed. Thus any sudden shock or vibration cannot defeat the opera tion of the lamp, as the feed must be arrested before the cores have reached the limit of travel.

The improvements herein described may be used either with direct or alternating currents. hen employed on the latter class of circuits, the split core, mounted as described, is elfective in damping vibration and reducing noise.

Having thus described my invention, what I claim, and desire to secure by Letters latout, is

1. An arc lamp having a frictional feedregulator, a magnet controlling the same, and regulating the length of the are and an. inde pendent stopping device for limiting the extent of slip of the friction mechanism.

2. An arc lamp having a wheel-train controlling the feed, a friction device eo-opcrat ing therewith, an arc-regulating magnet controlling said friction device to regulate the length of the are, a stop normally disengaged from the train, detents adapted to engage said step, and connections for interposin g the stop in the path of the detents when the magnet is aetuating the feeding devices.

An are lamp provided with a frictionwheel controlling the feed to regulate the length of the are, a magnet in. suitable relation to the arc to vary the friction, a circular series of detents revolved by the frictionwheel, and a stop interposed in the path of the detent when the magnet is in feeding position, substantially as described.

4. An arc lamp provided with a movable frame, a magnet for operating said frame to spring the are, a friction-wheel mounted in said frame, connections with the magnet core or armature for varying the friction with changes in the arc and thereby regulating the length of the arc, and a stop for limiting the amount of slip of said friction-wheel.

5. An arc lamp provided with a movable frame, a magnet for operating said frame to spring the are, a wheel-train mounted in the frame, a friction-shoe controlled by the magnet engaging a wheel of said train, and regu- THOS. SPENCER.

Witnesses:

FRANK S. MERE, EDWARD S. HUNT. 

